IPv6 subnet calculator

IPv6 CIDR range for fc00:21::101/128

Calculate the network address, final address, mask, and exact address capacity of any IPv6 CIDR prefix.

Example: 2606:4700::/32

Host bits are normalized to the network address before the range is calculated.

CIDR calculation

Network details for fc00:21::101/128

The prefix identifies a network with 0 host bits. Every address from the first address through the last address belongs to this range.

CIDR prefix

fc00:21::101/128

Network mask

ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff

Prefix length

/128

Host bits

0

First address

fc00:21::101

Last address

fc00:21::101

Total addresses

1

Total addresses (human readable)

2^0 addresses (1)

How this range is calculated

  1. 1The /128 prefix keeps the first 128 network bits fixed.
  2. 2Setting all 0 host bits to zero produces fc00:21::101.
  3. 3Setting those host bits to one produces fc00:21::101.

Network address

The normalized prefix base

CIDR notation describes a network, not a single host. If an address with host bits set is entered, this calculator normalizes it to the network base before calculating the range.

Expanded network address

fc00:0021:0000:0000:0000:0000:0000:0101

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